Another very formal style would be:
21 Delaware Place, Buffalo, N.Y., June 1, 189-.
Dear Miss Lothrop: In reply to your kind note, etc.
Truly yours,
George Harland.
To Miss Julia Lothrop,
110 Beacon Street, Boston, Mass.
The conclusion of a letter gives the writer fully as much latitude of style as the salutation. Some graceful little phrase should follow the subject-matter of the letter and lead up to the conclusion, thus:
I am, with love to the family, and remembrances to all my friends,
Yours cordially,
Mary Roe.